Auxiliary propulsion for ice-breaking vessels

ABSTRACT

A stamper or a plurality of stampers adapted to be periodically projected from a corresponding opening in the outer skin of the vessel, the axis of each stamper including an acute angle with the normal direction of movement of the vessel, and the bottom end of each stamper being provided with a pressure plate bearing at its lower surface barbs or pawls adapted to transmit the stamper forces onto the ice.

United States Patent 1 1 Waas 1 1 Oct. 2, 1973 [54] AUXILIARY PROPULSION FOR 3,033,543 5/1962 Bodine 299/14 ICE BREAKING VESSELS 2,995,103 8/1961 Waas et al. .4 114/40 3,437,381 4/1969 Bodine 299/14 [76] lnventor: Heinrich Waas, 33 Bramfelder Str.

164, Hamburg, Germany Primary Exammer-M1lt0n Buchler 1 1 Filed! g- 9, 1971 Assistant Examiner-Galen L. Barefoot Appl. No: 170,253

Foreign Application Priority Data Aug. 7, 1970 Germany P 20 39 258.9

References Cited UNITED STATES PATENTS Hayes et a1. 115/9 Att0rney-David Toren et a1.

[57] ABSTRACT A stamper or a plurality of stampers adapted to be periodically projected from a corresponding opening in the outer skin of the vessel, the axis of each stamper including an acute angle with the normal direction of move ment of the vessel, and the bottom end of each stamper being provided with a pressure plate bearing at its lower surface barbs or pawls adapted to transmit, the stamper forces onto the ice.

1 Claim, 3 Drawing Figures PATENTEDKIBT 2 3.762.354 SHEET 10F 2 Inventor: HEM/RIM HM Pmmzu $762,354

SHEET 2G? 2 Fig.3

In venfor: {IE/Mm H995 Mum AUXILIARY PROPULSION FOR ICE-BREAKING VESSELS DESCRIPTION OF THE INVENTION Marine vessels employed for ice-breaking are usually propelled by means of propellers or ships screws which basically do not differ from the propellers of other types of ships.

Although there are already known various types of propulsion means or auxiliary drives adapted specifically to the special circumstances of a passage through ice, such propulsion means have not been accepted generally. Examples of such propulsion means are beads mounted at the bow (German Patent No. 933,078) or wheels (German Patent No. 64,277). Al-

though the concept of front drives" which act directly on the ice which is to be broken is basically good, it has been rather difficult to translate this concept efficiently into practice. Propulsion devices of this type must be connected to the ships bow above and below the water line so that a strcture is obtained which must meet the demands of a sufficiently high rigidity to withstand heavy ice impacts and towering ice barriers and must be tight so as to prevent ice pieces or water from penetrating into the ship.

Another reason why the above-described types of special propulsion means did not find acceptance, particularly in arctic ice breaking operations, is as follows: Vessels adapted to ice-breaking in arctic marine areas must be sea-worthy on the long ice-free runs to get there. Bulky structures such as wheel or bead structures at the bow of the vessel interfere with the seaworthiness of the vessel. Moreover, when operating in the arctic ice, it is absolutely necessary to employ structures having a minimum susceptibility to trouble. This requirement likewise cannot be met by the abovementioned front drives.

Heretofore, the tendency in the development of icebreaking vessels. insofar as 'the propulsion is concerned. was in the direction of more and more powerful propellers which can act only indirectly onto the ice, by the force of the water that is accelerated by the propellers. Thereby rather low propulsion efficiencies have to be accepted which are due to the low cruising speeds in heavy ice. It is therefore the object of the present invention to overcome these drawbacks and to provide a novel and improved propulsion for ice-breaking vessels.

In the following, the invention will be described more in detail with reference to the appended drawings wherein FIG. I is a schematical cross-sectional elevational view of the bow of a vessel having an auxiliary propulsion in accordance with the present invention;

FIG. 2 is a schematical view of the bow of a vessel having only a conventional propulsion; and

FIG. 3 is a schematical cross-sectional elevational view of the bow of a vessel and showing more details ofthe auxiliary propulsion in accordance with the present invention.

Referring to FIG. I, the bow 2 of a vessel running up an ice sheet 1 is provided with an opening in the vessels outer skin at a point 3 at which the resistance of the still solid ice sheet is particularly effective. The opening in the vessel's outer skin is filled entirely by a stamper 4 which may be oscillated within a duct 5, the axis 6 of which extends at an acute angle to the direction of movement of the vessel. The stamper 4 is provided at its lower end with a pressure plate 7 by which pressure plate the stamper exerts a force 8 onto the ice sheet 1. The force 8 may be resolved into the component 9 (which runs perpendicular to the vessels outer skin) and the. component 10 (which extends parallel to the vessels outer skin). The forces exerted by the stamper 4 and the direction of movement thereof are periodically inverted. The pressure plate 7 is initially in an upper dead point position in which the plate 7 is flush with the vessels outer skin. From this initial position the pressure plate 7 moves downwardly and rearwardly and comes into a lower dead pointposition from which it again moves upwardly and forwardly into the initial position. This cycle is subsequently repeated.

FIG. 3 shows a schematical view of the construction of the propulsion. As may be noted from this view, a

detail that is essential to the propulsion effect is as follows: In order that the force component 10 which is responsible for the propulsion effect may act fully onto the ice, the pressure plate 7 is provided at its lower surface with barbs or pawls 11 which members come into the engagement position during the lifting stroke 12, and come into a sliding position during forward move ment. The propulsion; effect achieved thereby is similar to the one obtained with sealskins used for climbing by skiers. In these skins, the rearwardly pointing hairs act in the manner of pawls.

In accordance with the laws of mechanics, a high pro pulsion efficiency will be obtained with such a type of propulsion as long as the'propulsion may act onto the ice. The efficiency increases with decreasing vessel velocity, due to thick ice. Another effect 6yich is merived from the operation of the stamper drive improves the efficiency of the propulsion, and this effectmay be seen from a comparison of FIGS. 1 and 2. Oas already pointed out above, the bow of the vessel having a stamper drive runs up the ice sheet 1. For defining the forces exerted at the expected site of fracture 13, it is necessary to know the force components 9 and 10. Both force components tend to develop tensional stresses at the site of fracture, or in other words, both force components act in the same sense and thus support the breaking action onto the ice. In the bow of the vessel as shown in FIG. 2 which vessel is provided only with conventional propulsion means these relationships are quite different, as indicated in FIG. 2. The force 14 exerted by the skin of the vessel in a direction perpendicular onto the ice likewise results in a tensional stress at the site of fracture 13. The force component 15, however which is due to the friction between the vessels skin and'the ice produces a compressional stress. Therefore fracturing at point 13 is impeded since the effective stresses of both the force components are opposite to each other. This means that with propeller propulsion alone there will be required for breaking the ice a force acting perpendicularly onto the ice sheet which force must be higher than the one required in a stamper propulsion system.

Apart from the high efficiency of the propulsion according to the present invention, the high reliability of this propulsion is acharacterizing feature of the invention. The stampers are accessible from the interior of the vessel so that heat may be supplied to all movable parts coming into contact with the ice. Such heat may be supplied for example by the cooling water of the internal combustion engines of the vessel. This heat serves to protect the propulsion against icing. in the same manner, the adjacent portions of the skin of the vessel which are periodically subject to high ice pressures may be warmed up to reduced the frictional resistance at these portions.

The stamper drive should be generally most effective if the drive is located at the fore portion of the vessel. in comparison to prior art devices of icebreaker foreship propulsions, such as particularly foreship propeller, the proposed propulsion has the additional advantage that in the retracted condition the ships configuration under the water line is practically smooth. The proposed prop ulsion does not stop when the vessel pushes itself into the ice. Whereas heretofore arctic ice breakers designed for very thick ice could not be equipped with a bow propulsion that strongly enhances the propulsion and has also led to good results with ice breakers in the Baltic sea because the propellers and the propeller mountings cannot be designed so as to be retractable, the retractable stamper propulsion proposed by the present invention is a suitable bow propulsion. and this also with ice thicknesses up to the range of draft of the vessels.

Similar to screw propellers, it is advantageous to distribute the propulsion power, particularly in big vesels, onto several stampers which are mutually spaced transversely over the width of the vessel. By a suitable angle of inclination of the duct axis, every pressure plate may be made flush with the outer skin of the vessel. Furthermore a controller may be provided which controls the phase, the frequency and/or the amplitude of the stampers in a manner influencing the course of the ship or controlling the maximum force exerted by the vessel onto the ice. If there should be for example the risk of the vessel becoming stuck in the ice, it might be preferable to operate all stampers in phase to obtain a maximum impact. With normal ice conditions it should be more advantageous to operate the stampers in different phase relationships to obtain a more steady speed.

Any of a wide variety of drive means for the stamper may be employed such as unbalanced masses or cranks or pistons operated by an electrodynamic, a hydraulic or a thermodynamic drive. The following drives are particularly suitable:

a. The drive means shown schematically in FIG. 3.

This drive means consists essentially of counterrotating and electrically powered unbalanced masses 16 having a phase relationship so that only forces in the direction of the duct axis will be effective. Pressurized air may act onto a piston 17 which is connected to the stamper 4 in such a manner that the pressure plate 7 is in the upper dead point position approximately flush with the skin of the vessel.

b. A pile-driver of a type generally used in the construction field is arranged such that the rammer is moved in the direction of the axis 6 and thereby hits the stamper 4.. When retracting the rammer, the stamper will be likewise retracted upwardly by a spring means.

c. An electrodynamically actuated coil which is arranged concentrically to the axis 6 oscillates periodically an armature rigidly connected to the stamper 4 in the direction of the axis 6.

What is claimed is:

1. An auxiliary propulsion means for an ice-breaking vessel comprising a duct having an opening at least at one end with the opening arranged to be positioned in the plane of the skin of the vessel adjacent to its bow, said duct arranged to extend inwardly from the opening in the skin into the interior of the vessel, the axis of said duct arranged to extend at an acute angle to the direction of movement of the vessel and with the axis extending toward the opening being oriented generally rearwardly relative to the direction of movement of the vessel, a stamper positioned within said duct and being displaceable therethrough in the axial direction of said duct so that one end thereof can be projected outwardly from the skin of the vessel, a pressure plate extending transversely across the end of said stamper and arranged to project outwardly from the skin of the vessel, barbs positioned on and extending outwardly from said pressure plate so that they come into an engagement position when the end of said stamper is displaced outwardly from said duct and into a sliding position when said stamper is retracted into said duct, and

means for driving said stamper. 

1. An auxiliary propulsion means for an ice-breaking vessel comprising a duct having an opening at least at one end with the opening arranged to be positioned in the plane of the skin of the vessel adjacent to its bow, said duct arranged to extend inwardly from the opening in the skin into the interior of the vessel, the axis of said duct arranged to extend at an acute angle to the direction of movement of the vessel and with the axis extending toward the opening being oriented generally rearwardly relative to the direction of movement of the vessel, a stamper positioned within said duct and being displaceable therethrough in the axial direction of said duct so that one end thereof can be projected outwardly from the skin of the vessel, a pressure plate extending transversely across the end of said stamper and arranged to project outwardly from the skin of the vessel, barbs positioned on and extending outwardlY from said pressure plate so that they come into an engagement position when the end of said stamper is displaced outwardly from said duct and into a sliding position when said stamper is retracted into said duct, and means for driving said stamper. 